Railway cars have been used for many years to transport and sometimes store dry, bulk materials. Hopper cars (which have one or more hoppers), for example, are frequently used to transport coal, sand, metal ores, ballast, aggregates, grain and any other type of lading which may be satisfactorily discharged through respective openings formed in one or more hoppers.
Hopper cars may be classified as open or closed. Hopper cars may have relatively short sidewalls and end walls or relatively tall or high sidewalls and end walls. The sidewalls and end walls of many hopper cars are typically reinforced with a plurality of vertical side stakes. The sidewalls and end walls are typically formed from steel or aluminum sheets. Some hopper cars include interior frame structures or braces to provide additional support for the sidewalls.
Applicable standards of the Association of American Railroads (AAR) established maximum total weight on rail for any railcar including box cars, freight cars, hopper cars, gondola cars, and temperature-controlled cars within prescribed limits of length, width, height, etc. All railway cars operating on commercial rail lines in the U.S. must have exterior dimensions that satisfy associated AAR clearance plates. Therefore, the maximum load that may be carried by any railcar is typically limited by the applicable AAR clearance plate and empty weight of the railcar. Reducing the empty weight of a railcar or increasing the interior dimensions may increase both volumetric capacity and maximum load capacity of a railcar while still meeting applicable AAR standards for total weight on rail and clearance plate.
Railway cars often include one or more discharge openings. Hopper cars, for example, often include respective discharge openings at or near the bottom of each hopper to rapidly discharge cargo. As another example, gondola cars may have one or more discharge openings in a sidewall assembly of the gondola car. These discharge openings often have associated door and/or gate assemblies. A variety of door assemblies and gate assemblies along with various operating mechanisms have been used to open and close discharge openings associated with railway cars. There may be certain disadvantages associated with existing door assemblies and/or gate assemblies. For example, according to one existing approach, longitudinal door systems are operated by a pneumatic cylinder and drive beam located along the longitudinal centerline of the car. Although such an arrangement is suitable for some railcar operators, others may find that the placement of the discharge control system along the longitudinal centerline of the car may limit the purposes for which such a railcar may be used.
Thus, there is a need for an improved longitudinal door mechanism.